A resin molded product obtained by molding a thermoplastic resin is used for various products and parts since it has features such as easy molding and light-weight.
The resin molded product is sometimes bonded with other members depending on applications, etc. There have been known, as a method in which a resin molded product is bonded with other members, methods such as bonding with an adhesive, screw fastening, double-shot molding, hot plate welding, vibration welding, and laser welding. The bonding method is selected taking account of applications and shape of a resin molded product, and a preferable bonding method varies depending on applications, etc. Since it is difficult to use welding processing in the case of bonding with different type resins and metals, techniques such as adhesion, screw fastening, and staking are commonly employed.
An example of bonding a resin molded product with other members includes a case material (case material composed of a resin molded product) which houses a substrate including electronic parts mounted thereon (Patent Document 1). The reason why the substrate is housed in the case material is to relieve damage of electronic parts, caused by dusts and external impact, etc.
Electronic parts housed in the above case material are sometimes subjected to potting. The reason is to prevent electronic parts from rusting by moisture, etc. Examples of electronic parts subjected to the potting include various automobile electronic control systems, sensors, hybrid ICs for automobiles and electric appliances, and semiconductor parts, etc (Patent Document 2).
An adhesive is used to bond the case housing the above substrate and electronic parts with a lid, or to fix them in a case, and an epoxy-based composition and a silicone-based composition, etc. are known as potting agents used to apply potting. In the case of an integrated molded product to which heat resistance and cold resistance, etc. are required, an addition reaction type silicone-based composition (type in which curing is performed using a platinum catalyst) is preferably used. It is known that this addition reaction type silicone-based composition is also used as a sealing agent and a coating agent, etc., in addition to the above adhesive and potting agent.
In the case of using the addition reaction type silicon-based composition, when a phosphorus compound is contained in a resin molded product, this phosphorus compound inhibits an addition reaction due to a platinum catalyst (cure inhibition). As a result, when the addition reaction type silicone-based composition is used as an adhesive, adhesion between a resin molded product and other members is likely to be insufficient. When the addition reaction type silicone-based composition is used as a potting agent, malfunction of electronic parts due to rusts may occur since electronic parts are in contact with air due to cure inhibition.
Usually, the phosphorus compound is added for the purpose of imparting desired physical properties to a resin molded product, etc. For example, the phosphorus compound can be added to a resin as a flame retardant and a stabilizer, and exerts the effect of imparting flame retardance to a resin composition and preventing deterioration of physical properties or discoloration under high-temperature conditions. As mentioned above, the phosphorus compound is known as a useful additive, and the phosphorus compound is often contained in a resin composition as an essential component.
As mentioned above, the phosphorus compound is known as a useful additive, but it would be unsuited to be mixed in a resin molded product which is in contact with an addition reaction type silicone-based composition.
Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2004-343684
Patent Document 2: Japanese Unexamined Patent Application, Publication No. 2009-149736